Displaying publications 1 - 20 of 23 in total

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  1. Zakaria ZA, Mohamad AS, Chear CT, Wong YY, Israf DA, Sulaiman MR
    Med Princ Pract, 2010;19(4):287-94.
    PMID: 20516705 DOI: 10.1159/000312715
    OBJECTIVE: The present study was carried out to determine the antiinflammatory and antinociceptive activities of a methanol extract of Zingiber zerumbet rhizomes (MEZZ) using various experimental model systems.

    MATERIALS AND METHODS: The MEZZ was prepared by macerating oven-dried (50 degrees C) powdered rhizomes (1.2 kg) of Z. zerumbet in 80% methanol in a ratio of 1:20 (w/v) for 48 h. The supernatant was collected, filtered and evaporated to dryness under reduced pressure (50 degrees C) yielding approximately 21.0 g of the crude dried extract. The crude dried extract was stored at -20 degrees C prior to use and was dissolved in normal saline (0.9% NaCl) immediately before administration at concentrations required to produce doses of 25, 50 and 100 mg/kg.

    RESULTS: All dosages of MEZZ showed significant (p < 0.05) antiedema activity when assessed using the carrageenan-induced paw edema test and the cotton-pellet-induced granuloma test. The MEZZ exhibited significant (p < 0.05) antinociceptive activity when assessed by the writhing, hot plate and formalin tests. Pretreatment with naloxone (5 mg/kg) significantly decreased the latency of discomfort produced by the 100 mg/kg dose of MEZZ in the hot plate test.

    CONCLUSION: MEZZ produced antiinflammatory and antinociceptive activities which may involve the inhibition of bradykinin-, prostaglandin-, histamine- and opioid-mediated processes.

    Matched MeSH terms: Naloxone/pharmacology
  2. Shamima AR, Fakurazi S, Hidayat MT, Hairuszah I, Moklas MA, Arulselvan P
    Int J Mol Sci, 2012;13(9):11427-42.
    PMID: 23109863 DOI: 10.3390/ijms130911427
    Cannabinoids and opioids systems share numerous pharmacological properties and antinociception is one of them. Previous findings have shown that mitragynine (MG), a major indole alkaloid found in Mitragyna speciosa (MS) can exert its antinociceptive effects through the opioids system. In the present study, the action of MG was investigated as the antinociceptive agent acting on Cannabinoid receptor type 1 (CB1) and effects on the opioids receptor. The latency time was recorded until the mice showed pain responses such as shaking, licking or jumping and the duration of latency was measured for 2 h at every 15 min interval by hot plate analysis. To investigate the beneficial effects of MG as antinociceptive agent, it was administered intraperitoneally 15 min prior to pain induction with a single dosage (3, 10, 15, 30, and 35 mg/kg b.wt). In this investigation, 35 mg/kg of MG showed significant increase in the latency time and this dosage was used in the antagonist receptor study. The treated groups were administered with AM251 (cannabinoid receptor-1 antagonist), naloxone (non-selective opioid antagonist), naltrindole (δ-opioid antagonist) naloxonazine (μ(1)-receptor antagonist) and norbinaltorpimine (κ-opioid antagonist) respectively, prior to administration of MG (35 mg/kg). The results showed that the antinociceptive effect of MG was not antagonized by AM251; naloxone and naltrindole were effectively blocked; and norbinaltorpimine partially blocked the antinociceptive effect of MG. Naloxonazine did inhibit the effect of MG, but it was not statistically significant. These results demonstrate that CB1 does not directly have a role in the antinociceptive action of MG where the effect was observed with the activation of opioid receptor.
    Matched MeSH terms: Naloxone/pharmacology
  3. Ming-Tatt L, Khalivulla SI, Akhtar MN, Mohamad AS, Perimal EK, Khalid MH, et al.
    Basic Clin Pharmacol Toxicol, 2012 Mar;110(3):275-82.
    PMID: 21967232 DOI: 10.1111/j.1742-7843.2011.00804.x
    This study investigated the potential antinociceptive efficacy of a novel synthetic curcuminoid analogue, 2,6-bis-(4-hydroxy-3-methoxybenzylidene)cyclohexanone (BHMC), using chemical- and thermal-induced nociception test models in mice. BHMC (0.03, 0.1, 0.3 and 1.0 mg/kg) administered via intraperitoneal route (i.p.) produced significant dose-related inhibition in the acetic acid-induced abdominal constriction test in mice with an ID(50) of 0.15 (0.13-0.18) mg/kg. It was also demonstrated that BHMC produced significant inhibition in both neurogenic (first phase) and inflammatory phases (second phase) of the formalin-induced paw licking test with an ID(50) of 0.35 (0.27-0.46) mg/kg and 0.07 (0.06-0.08) mg/kg, respectively. Similarly, BHMC also exerted significant increase in the response latency period in the hot-plate test. Moreover, the antinociceptive effect of the BHMC in the formalin-induced paw licking test and the hot-plate test was antagonized by pre-treatment with the non-selective opioid receptor antagonist, naloxone. Together, these results indicate that the compound acts both centrally and peripherally. In addition, administration of BHMC exhibited significant inhibition of the neurogenic nociception induced by intraplantar injections of glutamate and capsaicin with ID(50) of 0.66 (0.41-1.07) mg/kg and 0.42 (0.38-0.51) mg/kg, respectively. Finally, it was also shown that BHMC-induced antinociception was devoid of toxic effects and its antinociceptive effect was associated with neither muscle relaxant nor sedative action. In conclusion, BHMC at all doses investigated did not cause any toxic and sedative effects and produced pronounced central and peripheral antinociceptive activities. The central antinociceptive activity of BHMC was possibly mediated through activation of the opioid system as well as inhibition of the glutamatergic system and TRPV1 receptors, while the peripheral antinociceptive activity was perhaps mediated through inhibition of various inflammatory mediators.
    Matched MeSH terms: Naloxone/pharmacology
  4. Zakaria ZA, Sani MH, Mohammat MF, Mansor NS, Shaameri Z, Kek TL, et al.
    Can J Physiol Pharmacol, 2013 Dec;91(12):1143-53.
    PMID: 24289087 DOI: 10.1139/cjpp-2013-0099
    This study was carried out to determine the antinociceptive activity of a novel synthetic oxopyrrolidine-based compound, (2R,3R,4S)-ethyl 4-hydroxy-1,2-dimethyl-5-oxopyrrolidine-3-carboxylate (ASH21374), and to elucidate the involvement of the opioid, vanilloid, glutamate, and nitric oxide - cyclic guanosine monophosphate (NO/cGMP) systems in modulating the observed antinociception. ASH21374, in the doses of 2, 10, and 100 mg/kg body mass, was administered orally to mice 60 mins prior to exposure to various antinociceptive assays. From the results obtained, ASH21374 exhibited significant (P < 0.05) antinociceptive activity in the abdominal constriction, hot-plate, and formalin tests that was comparable with 100 mg/kg acetylsalicylic acid or 5 mg/kg morphine, respectively. ASH21374 also attenuated capsaicin- and glutamate-induced paw licking. Pre-treatment with 5 mg/kg naloxone significantly (P < 0.05) inhibited the activity in all assays, while pretreatment with 10 mg/kg β-funaltraxamine, 1 mg/kg naltrindole, or 1 mg/kg nor-binaltorphimine significantly (P < 0.05) reversed the activity in the abdominal constriction test. l-Arginine, N(G)-nitro-l-arginine methyl esters (l-NAME), methylene blue, and their combinations, failed to inhibit the ASH21374 antinociceptive activity. In conclusion, ASH21374 demonstrated antinociceptive activities on the peripheral and central nervous systems, mediated through the activation of opioid receptors, inhibition of the glutamatergic system, and attenuation of vanilloid-mediated nociceptive transmission. Further studies have been planned to determine the pharmacological potential of ASH21374.
    Matched MeSH terms: Naloxone/pharmacology
  5. Ong HM, Mohamad AS, Makhtar N', Khalid MH, Khalid S, Perimal EK, et al.
    J Ethnopharmacol, 2011 Jan 7;133(1):227-33.
    PMID: 20920570 DOI: 10.1016/j.jep.2010.09.030
    Acmella uliginosa (Sw.) Cass. is a medicinal herbaceous plant that is commonly used by the Malay community in Malaysia to relieve pain often associated with mouth ulcers, toothache, sore throat, and stomach ache.
    Matched MeSH terms: Naloxone/pharmacology
  6. Sulaiman MR, Tengku Mohamad TA, Shaik Mossadeq WM, Moin S, Yusof M, Mokhtar AF, et al.
    Planta Med, 2010 Feb;76(2):107-12.
    PMID: 19637111 DOI: 10.1055/s-0029-1185950
    In the present study, the rhizome essential oil from Zingiber zerumbet (Zingiberaceae) was evaluated for antinociceptive activity using chemical and thermal models of nociception, namely, the acetic acid-induced abdominal writhing test, the hot-plate test and the formalin-induced paw licking test. It was demonstrated that intraperitoneal administration of the essential oil of Z. zerumbet (EOZZ) at the doses of 30, 100 and 300 mg/kg produced significant dose-dependent inhibition of acetic acid-induced abdominal writhing, comparable to that of obtained with acetylsalicylic acid (100 mg/kg). At the same doses, the EOZZ produced significant dose-dependent increases in the latency time in the hot-plate test with respect to controls, and in the formalin-induced paw licking test, the EOZZ also significantly reduced the painful stimulus in both neurogenic and inflammatory phase of the test. In addition, the antinociceptive effect of the EOZZ in the formalin-induced paw licking test as well as hot-plate test was reversed by the nonselective opioid receptor antagonist, naloxone suggesting that the opioid system was involved in its analgesic mechanism of action. On the basis of these data, we concluded that the EOZZ possessed both central and peripheral antinociceptive activities which justifying its popular folkloric use to relieve some pain conditions.
    Matched MeSH terms: Naloxone/pharmacology
  7. Sulaiman MR, Zakaria ZA, Daud IA, Ng FN, Ng YC, Hidayat MT
    J Nat Med, 2008 Apr;62(2):221-7.
    PMID: 18404328 DOI: 10.1007/s11418-007-0210-3
    This study was performed to determine the antinociceptive and anti-inflammatory activities of aqueous extract of Kaempferia galanga leaves using various animal models. The extract, in the doses of 30, 100, and 300 mg/kg, was prepared by soaking (1:10; w/v) the air-dried powdered leaves (40 g) in distilled water (dH(2)O) for 72 h and administered subcutaneously in mice/rats 30 min prior to the tests. The extract exhibited significant (P < 0.05) antinociceptive activity when assessed using the abdominal constriction, hot-plate and formalin tests, with activity observed in all tests occurring in a dose-dependent manner. Furthermore, the antinociceptive activity of K. galanga extract was significantly (P < 0.05) reversed when prechallenged with 10 mg/kg naloxone. The extract also produced a significantly (P < 0.05) dose-dependent anti-inflammatory activity when assessed using the carrageenan-induced paw-edema test. In conclusion, this study demonstrated that K. galanga leaves possessed antinociceptive and anti-inflammatory activities and thus supports the Malay's traditional uses of the plant for treatments of mouth ulcer, headache, sore throat, etc.
    Matched MeSH terms: Naloxone/pharmacology
  8. Sulaiman MR, Zakaria ZA, Kamaruddin A, Meng TF, Ali DI, Moin S
    Methods Find Exp Clin Pharmacol, 2008 Nov;30(9):691-6.
    PMID: 19229377 DOI: 10.1358/mf.2008.30.9.1305824
    Trigonopleura malayana L. (Euphorbiaceae) resin, locally known as Gambir Sarawak, has been used traditionally to alleviate pain associated with insect bites, muscle ache, toothache and minor injuries. The present study was carried out using various animal models to determine the antinociceptive and antiinflammatory activities of the T. malayana resin aqueous extract. Antinociceptive activity was measured using the abdominal constriction, hot plate and formalin tests, while antiinflammatory activity was measured using the carrageenan-induced paw edema test. The extract, obtained after 24 h of soaking the dried resin in distilled water, was prepared in doses of 0.3, 3 and 10 mg/kg and administered subcutaneously 30 min prior to the assays. The mechanism of action was also determined by prechallenging with naloxone (10 mg/kg), a nonselective opioid antagonist. The extract was found to exhibit significant (P < 0.05) and dose-dependent antinociceptive and antiinflammatory activities; naloxone failed to inhibit the former activity. In conclusion, the aqueous extract of T. malayana resin possesses nonopioid antinociceptive and antiinflammatory activities, thus supporting previous claims regarding its traditional use by the Malays to treat various ailments, particularly those related to pain.
    Matched MeSH terms: Naloxone/pharmacology
  9. Nabishah BM, Morat PB, Khalid BA, Kadir BA
    Clin Exp Pharmacol Physiol, 1990 Dec;17(12):841-7.
    PMID: 2092952
    1. The effects of corticosteroid pretreatment on acetylcholine (ACH)-induced contraction of bronchial smooth muscle (BSM) were studied. 2. ACH dose-response curves for dexamethasone (DM)- and corticosterone (B)-treated but not deoxycorticosterone (DOC)-treated BSM were significantly shifted to the right; this provides evidence that glucocorticoid treatment reduced the sensitivity of BSM to ACH. 3. Morphine enhanced BSM contraction in response to ACH by 20%. DM suppressed this enhancement. 4. These findings correlated well with the reduction of muscarinic receptor numbers in BSM by glucocorticoids in our previous study. In addition, glucocorticoids reduced the sensitivity of BSM to opioids.
    Matched MeSH terms: Naloxone/pharmacology
  10. Zakaria ZA, Sulaiman MR, Mat Jais AM, Somchit MN
    Can J Physiol Pharmacol, 2005 Jul;83(7):635-42.
    PMID: 16091789
    The effects of an aqueous supernatant of haruan (ASH) (Channa striatus) fillet extract on various antinociception receptor system activities were examined using a mouse abdominal-constriction model. Mice that were pretreated with distilled water, s.c., followed 10 min later by administration of 25%, 50%, and 100% concentration ASH, s.c., produced a significant concentration-dependent antinociceptive activity (p < 0.001). Pretreatment with naloxone (0.3, 1.0, and 3.0 mg/kg body mass), 10 min before ASH administration, failed to block the extract antinociception. Pretreatment of the 100% concentration ASH with mecamylamine (5 mg/kg), pindolol (10 mg/kg), and haloperidol (1 mg/kg) also did not cause any significant change in its antinociception. However, pretreatment with atropine (5 mg/kg), bicuculline (10 mg/kg), phenoxybenzamine (10 mg/kg), and methysergide (5 mg/kg) were found to reverse ASH antinociception. Based on the above findings, the ASH is suggested to contain different types of bioactive compounds that act synergistically on muscarinic, GABAA, alpha-adrenergic, and serotonergic receptor systems to produce the observed antinociception.
    Matched MeSH terms: Naloxone/pharmacology
  11. Ainsah O, Nabishah BM, Osman CB, Khalid BA
    Clin Exp Pharmacol Physiol, 1999 7 1;26(5-6):433-7.
    PMID: 10386234
    1. The present study examined the effect of naloxone (NAL), glycyrrhizic acid (GCA), deoxycorticosterone (DOC) and dexamethasone (DEX) on daily repeated 2 h chronic restrained stress (RS) on the locomotor activity (LA) of rats tested in the open field arena to elucidate the possible roles of opioids, glucocorticoids and mineralocorticoids in response to stress. 2. Intact and adrenalectomized (ADX) rats were either injected with 0.1 mL of NAL (0.32 microgram/100 g BW), 2.4 mg/kg DOC or 120 micrograms/kg DEX or had 1.0 mg/mL GCA dissolved in their drinking water or normal saline (for the ADX group) dissolved in their drinking water. 3. In intact groups, treatment with NAL completely blocked the stress response and treatment with GCA, DOC and DEX partially prevented the stress response. Adaptation occurred on either days 4, 5, 6 or 7 for intact rats treated with DEX, DOC, GCA or control rats, respectively. All ADX control rats died following the first 2 h RS. Adrenalectomized rats treated with DEX or DOC adapted later compared with intact rats, while rats given either GCA or NAL were unable to block or adapt to chronic RS. 4. These findings demonstrate that the stress response is primarily mediated by endogenous opioids, in that it is blocked by NAL. Both mineralocorticoids and glucocorticoids, which can act centrally to inhibit endorphins, partially blocked the stress response. The effect of GCA in intact rats was similar to that of both DEX and DOC in intact rats. Adrenalectomized rats treated with GCA (despite their lack of endogenous corticosterone) showed a stress response that was significantly different from the other ADX groups, implying that GCA had effects independent of endogenous corticosterone.
    Matched MeSH terms: Naloxone/pharmacology*
  12. Kamilla L, Ramanathan S, Sasidharan S, Mansor SM
    Indian J Pharmacol, 2014 Sep-Oct;46(5):515-20.
    PMID: 25298581 DOI: 10.4103/0253-7613.140583
    Clitoria ternatea Linn. (C. ternatea) is an Ayurvedic herb traditionally used as medicine to relieve inflammatory, rheumatism, ear diseases, fever, arthritis, eye ailments, sore throat and body ache. This study aims to evaluate and elucidate the possible mechanism underlying the antinociceptive action of methanolic extracts of C. ternatea leaf and root using several antinociception models.
    Matched MeSH terms: Naloxone/pharmacology
  13. Sulaiman MR, Hussain MK, Zakaria ZA, Somchit MN, Moin S, Mohamad AS, et al.
    Fitoterapia, 2008 Dec;79(7-8):557-61.
    PMID: 18672036 DOI: 10.1016/j.fitote.2008.06.005
    The aqueous extract of Ficus deltoidea leaves was evaluated for possible antinociceptive activity in three models of nociception, namely, acetic acid-induced abdominal writhing, formalin and hot plate test. The results of the present study showed that intraperitoneal administration of the F. deltoidea leaves aqueous extract at the dose of 1, 50 and 100 mg/kg, 30 min prior to pain induction produced significant dose-dependent antinociceptive effect in all the models used, which indicating the presence of both central and peripherally mediated activities. Furthermore, the antinociceptive effect of the extract in the formalin and hot plate test was reversed by the non-selective opioid receptor antagonist naloxone suggesting that the endogenous opioid system is involved in its analgesic mechanism of action. Thus, the present results demonstrated that F. deltoidea leaves aqueous extract contains pharmacologically active constituents which possess antinociceptive activity justifying its popular therapeutic use in treating conditions associated with the painful conditions.
    Matched MeSH terms: Naloxone/pharmacology
  14. Khalid S, Shaik Mossadeq WM, Israf DA, Hashim P, Rejab S, Shaberi AM, et al.
    Med Princ Pract, 2010;19(4):255-9.
    PMID: 20516700 DOI: 10.1159/000312710
    To study the effects of Tamarindus indica L. aqueous fruit extract on the antinociceptive activities in rodent models.
    Matched MeSH terms: Naloxone/pharmacology
  15. Ruszymah BH, Nabishah BM, Aminuddin S, Khalid BA
    Clin Exp Pharmacol Physiol, 1995 Jan;22(1):35-9.
    PMID: 7768032
    1. The aim of this study was to investigate the effect of repeated exposure to stress on tail blood pressure (TBP) of normal as well as GCA (glycyrrhizic acid) and steroid treated rats. Male Sprague-Dawley rats (250 g) were exposed to ether vapour to achieve light anaesthesia prior to TBP recording. Rats were injected with either normal saline or naloxone prior to exposure to stress. Tail blood pressure was recorded daily for 2 weeks. 2. We found that ether stress caused a transient drop in TBP in control as well as in dexamethasone (DEX) treated rats. The stress-induced fall in blood pressure was reduced by naloxone in control rats but not in DEX treated rats. However the transient drop in TBP following stress was not seen in either GCA or deoxycorticosterone (DOC) treated rats. 3. We conclude that first, the reduction in TBP was due to the release of endogenous opioids caused by stress. Second, DOC may block the release of such endogenous opioids, preventing the drop in TBP in response to stress, while DEX did not. Third, GCA caused a similar mineralocorticoid effect on reversing stress induced hypotension.
    Matched MeSH terms: Naloxone/pharmacology
  16. Ainsah O, Nabishah BM, Osman CB, Khalid BA
    PMID: 10595599
    Normal rats, on being repetitively stressed by being restrained in a tight container for two hours, had higher levels of plasma corticosterone compared to pre stress values. These rats also reacted to the stress by a behavioral response in which there was marked decrease in locomotor activity assessed by the open field test (pre stress: 71.3 +/- 2.6 squares crossed versus post stress: 14.3 +/- 2.5 squares crossed) by counting the number of squares entered by the rat over 5 minutes. By the 6th to 7th exposures to the repetitive stress, the rats adapted to the stress and had normal plasma corticosterone levels and locomotor activity scores comparable to the pre stress values. These responses to stress were completely blocked by the administration of 0.32 microg/100 g BW of naloxone i.p at 10 minutes prior to the stress. In rats fed with rat chow supplemented with 90 mg/kg rat chow or 150 mg/kg rat chow of vitamin E, there was significant reduction of the plasma corticosterone levels and improvement in the locomotor activity. Stress thus caused opioid mediated increase in plasma corticosterone and reduction in locomotor activity which could be blocked by naloxone. These stress responses probably also involved generation of oxygen free radicals which were scavenged by the vitamin E, thus reducing the effects of repetitive stress on locomotor activity and serum corticosterone levels.
    Matched MeSH terms: Naloxone/pharmacology*
  17. Yusoff NHM, Mansor SM, Müller CP, Hassan Z
    Behav Brain Res, 2017 08 14;332:1-6.
    PMID: 28559179 DOI: 10.1016/j.bbr.2017.05.059
    Mitragynine is the main psychoactive ingredient of the herbal drug preparation Kratom (Ketum), derived from the plant Mitragyna speciosa. Kratom is a widely abused drug in Southeast Asian and has a psychostimulant profile at low-medium doses, while high doses have opioidergic effects. Mitragynine was shown to possess opiate receptor affinity. However, its role in the behavioural effects of mitragynine is unclear. Here we asked whether the reinforcing effects of mitragynine are mediated by opiate receptors using a conditioned place preference (CPP) paradigm in rats. In the first experiment we tested the effects of the opiate receptor antagonist naloxone (0.1, 0.3 and 1.0mg/kg) on the acquisition of mitragynine (10mg/kg)-induced CPP. In the second experiment, we tested the involvement of opiate receptors in the expression of mitragynine-induced CPP in rats. We found that naloxone suppresses the acquisition of mitragynine-induced CPP. This effect was already evident at a dose of naloxone (0.1mg/kg) which, by itself, had no conditioned place aversion (CPA) effect. Higher doses of naloxone induced a CPA and blocked mitragynine-induced CPP. In contrast, naloxone had no effect on the expression of mitragynine-induced CPP. These findings suggest that the acquisition, but not the expression of the reinforcing effects of mitragynine is mediated by opiate receptors.
    Matched MeSH terms: Naloxone/pharmacology
  18. Davoudi M, Vijeepallam K, Azizi H, Mirnajafi-Zadeh J, Semnanian S
    J Neural Transm (Vienna), 2019 11;126(11):1425-1435.
    PMID: 31493096 DOI: 10.1007/s00702-019-02064-2
    The locus coeruleus (LC) as a target of addictive drugs receives a dense projection of orexinergic fibres from the lateral hypothalamus (LH) and is accordingly a candidate site for the expression of the somatic aspects of morphine withdrawal. Recently it has been shown that the inhibitory synaptic currents of LC neurons decrease partly through orexin type 1 receptors in the context of naloxone-induced morphine withdrawal; however, its cellular mechanism remains unclear. In this study, whole-cell patch clamp recordings of LC neurons in brainstem slices were used to investigate the impact of protein kinase C (PKC) on GABAergic inhibitory post-synaptic currents (IPSCs) in the context of naloxone-induced morphine withdrawal. Male Wistar rats (P14-P21) received morphine (20 mg/kg, i.p.) daily for 7 consecutive days to induce morphine dependency. Our results showed that the application of PKC inhibitor (Go 6983; 1 µM) alone did not decrease the probability of GABA release in the LC neurons of the morphine-treated rats in the presence of naloxone. Although, Go 6983 reversed the reduction of the amplitude of evoked IPSCs (eIPSCs) and spontaneous IPSCs (sIPSCs) frequency induced by orexin-A but did not change the sIPSCs amplitude. These results indicate that the suppressive effect of orexin-A on IPSCs is probably reversed by PKC inhibitor in the LC neurons of morphine-treated rats in the context of naloxone withdrawal.
    Matched MeSH terms: Naloxone/pharmacology*
  19. Johari IS, Harun N, Sofian ZM, Shoaib M
    Psychopharmacology (Berl), 2021 Nov;238(11):3183-3191.
    PMID: 34333672 DOI: 10.1007/s00213-021-05934-4
    RATIONALE: Kratom (Mitragyna speciosa Korth), a native medicinal plant of Southeast Asia, is proposed to exhibit potential therapeutic value as an opioid substitute. However, studies of its negative emotional states resulting from withdrawal particularly of its main psychoactive compound, mitragynine (MG), are limited.

    OBJECTIVES: Using the pentylenetetrazol (PTZ) discrimination assay, this study aims to investigate the effects of MG in responding to the PTZ stimulus and to assess the generalisation effects of withdrawal from MG to the PTZ stimulus.

    METHODS: Rats (n = 20) were trained on a tandem (FR-10, VI-15) schedule of food reinforcement to press one lever after administration of the anxiogenic compound PTZ (16 mg/kg, i.p.) and an alternate lever after vehicle. Following acute tests, training was suspended, and rats were chronically treated with MG or morphine at 8-h intervals for 9 days and withdrawal was precipitated on the tenth day using naloxone (1 mg/kg, i.p.). The rats were tested for generalisation to PTZ at 2, 8 and 24 h after the last dose of MG or morphine administration.

    RESULTS: Unlike morphine that produced dose-related PTZ-like stimulus, MG at 3, 10, 30 and 45 mg/kg doses showed no substitution to the PTZ discriminative stimulus. In contrast to morphine which produced a time-dependent generalisation to the PTZ stimulus, naloxone did not precipitate withdrawal effects in MG-treated rats as they selected the vehicle lever at three withdrawal time points.

    CONCLUSION: These results demonstrate that MG produces a very different response to morphine withdrawal that is not associated with anxiogenic-like subjective symptoms. These characteristics of MG may provide further support for use as a novel pharmacotherapeutic intervention for managing opioid use disorder.

    Matched MeSH terms: Naloxone/pharmacology
  20. Sulaiman MR, Perimal EK, Zakaria ZA, Mokhtar F, Akhtar MN, Lajis NH, et al.
    Fitoterapia, 2009 Jun;80(4):230-2.
    PMID: 19535012 DOI: 10.1016/j.fitote.2009.02.002
    We have investigated the antinociceptive activity of zerumbone (1), a natural cyclic sesquiterpene isolated from Zingiber zerumbet Smith, in acetic acid-induced abdominal writhing test and hot plate test in mice. 1 given by intraperitoneal route produced significant dose-dependent antinociceptive effect in all the test models used. In addition, the antinociceptive effect of 1 in the hot plate test was reversed by the non-selective opioid receptor antagonist naloxone, suggesting that the opioid system is involved in its analgesic mechanism of action.
    Matched MeSH terms: Naloxone/pharmacology
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